About the Shingle Calculator
Asphalt shingles are the most common roofing in North America. They are sold in bundles — packs light enough to carry up a ladder — and priced and estimated by the square, which is 100 square feet of roof. Most shingles are packed three bundles to the square.
A shingle order is more than the shingles for the main roof surface, though. The first row along the eaves sits on a starter strip; every ridge and hip is finished with cap shingles; and every shingle is held down by roofing nails. Leaving any of these off the order means a second trip to the supplier with the roof half-finished.
This shingle calculator turns the roof area into bundles, with waste, and counts the hip and ridge cap bundles, starter strip bundles and nails.
How to Use the Shingle Calculator
Choose imperial or metric.
Enter the roof area — the sloped area, not the floor plan. The roofing calculator works this out from the building's footprint and pitch.
Choose the shingle type and check the bundles per square on the wrapper.
Set the waste allowance: about 10% for a simple gable roof, 15% or more for hips, valleys and dormers.
Optionally, enter the total length of hips and ridges and of eaves and rakes, and the linear coverage of a bundle of cap and starter shingles.
Tick high-wind area if six nails per shingle are required.
How the Bundles Are Worked Out
squares = roof area ÷ 100 ft² × (1 + waste %)
bundles = squares × bundles per square, rounded up
caps = hip and ridge length ÷ cap bundle coverage, rounded up
starter = eaves and rake length ÷ starter bundle coverage, rounded up
nails = bundles × shingles per bundle × nails per shingleStep-by-Step Example
A 1,503 ft² roof, architectural shingles, 3 bundles per square, 10% waste, 42 ft of ridge, 156 ft of eaves and rakes.
Squares: 1,503 ÷ 100 × 1.10 = 16.53
Bundles: 16.53 × 3 = 49.6 → 50 bundles
Ridge caps: 42 ÷ 25 ft per bundle = 1.7 → 2 bundles
Starter: 156 ÷ 105 ft per bundle = 1.5 → 2 bundles
Nails: 50 × 22 × 4 = 4,400 nailsBundles per Square
3-tab shingles — the traditional flat shingle with three tabs — and most architectural or laminated shingles are packed three bundles to a square, so each bundle covers about 33.3 ft². Some heavy designer shingles, which imitate slate or shake with thicker layers, come four or five bundles to the square. Always check the coverage printed on the wrapper; the calculator takes whatever number you enter.
Hip and Ridge Caps
Ridges and hips are covered by a row of cap shingles, each bent over the peak and overlapping the next. Architectural shingles are too thick and layered to bend, so they need matching cap bundles, which typically cover 20 to 33 linear feet each. With 3-tab shingles, caps can be cut from full shingles — three per shingle — though purpose-made caps give a neater, more durable ridge.
Measure the length of every ridge and every hip, add them, and divide by the coverage on the cap bundle.
Starter Strip
The first course along the eaves needs a starter: a strip with a sealant line near the edge that glues the first row of shingles down, so wind cannot get under it. Many manufacturers also recommend starter along the rakes — the sloping gable edges. Measure these edges and divide by the linear coverage of a starter bundle, often 100 to 120 feet.
Nailing
The standard pattern is four nails per shingle, placed in the nailing strip marked on the shingle. In high-wind regions, on steep roofs, or where the manufacturer or code requires it, use six. Architectural shingles run about 22 per bundle and 3-tab about 26, so a square takes roughly 260 to 320 nails with four per shingle. Nails should be long enough to penetrate the roof deck — 1¼ in (32 mm) galvanised roofing nails are typical for new roofs.
Other Materials
A complete reroof also needs underlayment over the whole deck, an ice-and-water membrane at the eaves and in valleys in cold climates, drip edge along the eaves and rakes, flashing around chimneys and walls, and ventilation at the ridge or soffits. The roofing calculator gives the underlayment area.
Storing and Handling Bundles
Bundles are heavy — around 60 to 80 lb (27 to 36 kg) each for architectural shingles — so a full roof's worth weighs well over a tonne. Have them delivered as close to the roof as possible, ideally lifted onto it by the supplier's boom, and spread them along the ridge rather than stacking them in one place.
Store bundles flat, off the ground and under cover, and do not stack them more than the wrapper allows; bent or curled shingles do not lie flat. In cold weather the shingles become brittle and the sealant strips will not bond until the sun warms them, so many manufacturers recommend hand-sealing below about 40 °F (4 °C). In hot weather, avoid walking on freshly laid shingles more than you have to, as the granules scuff off easily.
Understanding Your Result
Bundles is the number of bundles of field shingles, including waste.
Squares shows the squares with waste and the bundles per square used.
Hip and ridge cap and Starter strip give those bundles.
Nails estimates the roofing nails.
Worth knowing covers batches and bundle coverage.
When Should You Use This Calculator?
Ordering shingles for a reroof, including the accessories.
Checking a roofer's material list.
Comparing 3-tab and architectural shingles.
After the roofing calculator, to turn squares into a shopping list.
Common Mistakes
Using floor area instead of roof area.
Forgetting ridge caps and starter strip.
Assuming three bundles per square. Check the wrapper.
Too little waste on a complicated roof.
Mixing production lots. The colour blend can vary.